Unix Timestamp Converter
Convert between Unix timestamps and human-readable dates in any timezone, with millisecond precision.
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Frequently asked questions
Is any data sent to a server when I use this tool?
Why does the Unix epoch start on January 1, 1970?
What is the Y2K38 problem?
What is the difference between seconds and milliseconds timestamps?
How do I avoid precision loss when working with timestamps?
What is ISO 8601 and why should I use it?
Can I convert dates before 1970?
How does timezone conversion work?
Which timestamp values are worth memorising?
Does a Unix timestamp include timezone information?
About Unix Timestamp Converter
The Unix timestamp is a single integer that counts the number of seconds elapsed since January 1, 1970, 00:00:00 UTC — a moment known as the Unix Epoch. This system was established by the early Unix developers at Bell Labs because they needed a compact, timezone-neutral way to represent points in time across networked machines. The choice of 1970 was largely practical: it was a recent, round year that fell well within the range of 32-bit integers, and the earliest Unix systems were being developed in that era. Today, the Unix timestamp is the universal language of time for virtually every operating system, database, API, and programming language on the planet.
Developers encounter Unix timestamps constantly: JWT tokens carry an exp (expiration) field in epoch seconds, HTTP headers use them for cache control, database schemas store event times as integers for fast indexing, log aggregation systems like Elasticsearch index timestamps for range queries, and mobile apps sync state across devices using epoch-based change vectors. Scientists and data analysts use timestamps to align time-series datasets from different sources. Even everyday users run into them in web URLs, file metadata, and cookie expiry fields — often without realising it.
This tool converts between raw Unix timestamps and human-readable date strings entirely within your browser. No data is ever sent to a server. You can paste a 10-digit seconds-precision timestamp or a 13-digit milliseconds-precision one — the tool auto-detects the format. It also shows the current live timestamp, lets you pick any IANA timezone from a searchable dropdown, and outputs the date in both ISO 8601 and a localized format for quick reading.
A few important edge cases to be aware of: JavaScript's Date object works in milliseconds, so always divide by 1000 when comparing with a seconds-based API. Negative timestamps represent dates before 1970 and are fully supported. The Y2K38 problem is a looming issue for systems that store timestamps as a signed 32-bit integer — such systems will overflow on January 19, 2038 at 03:14:07 UTC, wrapping around to a date in 1901. Most modern 64-bit systems are immune, but embedded hardware and legacy databases may still be at risk. When working across timezones, always store and transmit timestamps in UTC and convert to local time only for display.
From Bell Labs to Every Device on Earth: The Story of the Unix Epoch
The Unix operating system was born in the late 1960s at AT&T's Bell Labs, created by Ken Thompson, Dennis Ritchie, and colleagues. When they needed a way to track file modification times and schedule processes, they devised the epoch-based timestamp system. The specific date of January 1, 1970 was not chosen for any grand reason — it was simply a round number close to when the system was being built, and it fit neatly in the 32-bit integers that were the practical limit of the hardware of the day.
The 32-bit timestamp limitation is the root of the Year 2038 problem, sometimes called Y2K38 or the Unix Millennium Bug. A signed 32-bit integer maxes out at 2,147,483,647, which corresponds to 03:14:07 UTC on January 19, 2038. After that second, the counter overflows to -2,147,483,648 — which maps to December 13, 1901. Engineers have been quietly patching this for years: the Linux kernel moved to 64-bit timestamps, and most modern databases and languages have followed. However, billions of embedded devices, industrial controllers, and legacy systems may never receive updates.
JavaScript took the epoch concept and multiplied it by 1,000, working in milliseconds rather than seconds since the language was designed for interactive web interfaces where sub-second timing matters. This is why Date.now() returns a 13-digit number. Other languages made different choices: Python's time.time() returns a floating-point seconds value, Go's time.UnixNano() works in nanoseconds, and SQL databases often store timestamps as formatted strings — all referring to the same underlying concept that two programmers at Bell Labs improvised over half a century ago.